JPH0799113B2 - Stratified combustion control system for engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stratified combustion control device for an engine that stratifies the combustion chamber so that the combustible mixture is unevenly distributed around a spark plug in the combustion chamber and burns the mixture. Regarding the improvement of.

(Prior Art) Conventionally, as a stratified charge combustion control device for an engine of this type, for example, as disclosed in JP-A-60-36721, the operating state of the engine is detected, and at the time of low load operation,
A small amount of fuel is supplied to the combustion chamber, and this fuel is unevenly distributed around the spark plug in the combustion chamber to perform stratified combustion of the air-fuel mixture, thereby ensuring combustion stability and the air-fuel ratio of the air-fuel mixture as a whole. (Lean) to improve fuel efficiency, stop the above-mentioned stratified combustion when the engine is operating under high load, and evenly distribute the amount of fuel (combustible mixture) according to the operating condition in the combustion chamber. It is known to disperse and uniformly burn an air-fuel mixture to ensure an increase in its output.

And in the above-mentioned conventional one, the throttle valve opening of the engine can be adjusted independently from the operation of the accelerator operation member in order to significantly increase the air-fuel ratio at the time of stratified combustion of the air-fuel mixture,
During stratified combustion of the air-fuel mixture, the throttle valve opening is fully opened to significantly increase the intake air amount to significantly increase the air-fuel ratio of the air-fuel mixture, while during uniform combustion of the air-fuel mixture, the throttle valve is opened normally. Degree is adjusted to a required opening degree according to the operation amount of the accelerator operation member, and the intake air amount is controlled to an amount according to the accelerator operation amount.

(Problems to be Solved by the Invention) By the way, when the stratified combustion and the uniform combustion of the air-fuel mixture are performed according to the operating state as described above, at the time of uniform combustion, the fuel amount corresponding to the intake air amount is changed to the combustion chamber. Although the air-fuel mixture is uniformly distributed and uniformly supplied to the whole, the transition of the transition from uniform combustion to stratified combustion is viewed microscopically. The throttle valve opening is adjusted to fully open to increase the air-fuel ratio and the intake air amount is significantly increased, especially when uniform combustion of the air-fuel mixture is stopped. If the operation to fully open the throttle valve opening is started during the transition to, the air-fuel ratio becomes over lean due to the sudden increase in the intake air amount, and the combustibility of the air-fuel mixture deteriorates. Loss if the degree is high There is a fear of causing a fire. (Note that, conversely to the above, during the transition transition from stratified charge combustion to uniform combustion of the air-fuel mixture, even when the throttle valve opening is closed and the intake air amount suddenly decreases during the transition to stop of stratified charge combustion,
Since the fuel amount is a small amount that is unevenly distributed around the spark plug, it does not become overrich and the combustibility of the air-fuel mixture is secured well).

The present invention has been made in view of the above circumstances, and an object thereof is to perform a combustion switching transient between uniform combustion and stratified combustion when performing stratified combustion and uniform combustion of an air-fuel mixture according to an engine operating state. Sometimes, by correlating the switching of fuel supply to the combustion chamber and the switching of the throttle valve opening,
It is to prevent the air-fuel ratio from becoming over lean due to the full opening of the throttle valve even during the transition transition from the uniform combustion of the air-fuel mixture to the stratified charge combustion, thereby ensuring good combustibility of the air-fuel mixture.

(Means for Solving Problems) In order to achieve the above object, a solution means of the present invention is an engine that performs stratified combustion and uniform combustion of an air-fuel mixture, that is, an operating state of the engine as shown in FIG. When the engine operating state is in the first operating range such as the low load operating range, the fuel is supplied around the ignition plug of the combustion chamber. While the air-fuel mixture is stratified and burned, when the engine operating condition is in a second operating region such as a high load operating region different from the first operating region, fuel is supplied to the entire combustion chamber to uniformly burn the air-fuel mixture. It is premised on an engine stratified combustion control system including a fuel supply means (42). When the engine operating state is in the first operating range, the throttle valve opening is fully opened by receiving the outputs of the opening adjusting means 20 for adjusting the opening of the throttle valve 9 of the engine and the operating state detecting means 34. On the other hand, in the second operation range, from the uniform combustion to the stratified charge combustion together with the opening degree control means 44 for controlling the opening degree adjusting means 20 so as to obtain the required opening degree according to the operation amount of the accelerator operation member. Of the fuel supply switching time detecting means 45 for detecting the transition time of the fuel supply switching, and the throttle valve 9 after receiving the output of the fuel supply switching time detecting means 45 and switching the fuel supply from the uniform combustion to the stratified combustion. And a correction unit 46 that corrects the control of the opening adjustment unit 20 by the opening control unit 44 so that the opening amount is fully opened.

(Operation) According to the present invention, in the present invention, in the first operating region such as the low load operating region of the engine, the fuel is supplied eccentrically around the ignition plug of the combustion chamber by the fuel supply means 42, and the throttle valve 9 Since the stratified charge combustion of the air-fuel mixture is performed in a state in which the opening degree is controlled to be fully opened by the opening degree control means 44, the air-fuel ratio of the air-fuel mixture as a whole becomes remarkably large, and the improvement of fuel efficiency is effective. Planned for.

Further, in the second operating range such as the high load operating range of the engine, the fuel is uniformly distributed and supplied to the entire combustion chamber by the fuel supply means 42, and the opening degree of the throttle valve 9 is controlled by the opening degree control means 44. Since the opening degree is controlled to the required opening degree according to the operation amount of the accelerator operation member and the uniform combustion of the air-fuel mixture is performed in this state, the output of the engine can be increased according to the driver's request.

At the transition of the engine operating state from the second operating region to the first operating region and the combustion state of the air-fuel mixture is switched from uniform combustion to stratified combustion, the fuel supply means 42 conducts stratified combustion of the air-fuel mixture into stratified combustion. After the fuel supply to the combustion is completely switched, the opening degree of the throttle valve 9 is controlled to be fully open for the first time by the correction of the control by the correction means 46. In other words, in the transient state in which the uniform combustion of the air-fuel mixture is still continuing, the opening degree of the throttle valve 9 is still maintained at the opening degree according to the accelerator operation amount, which may cause over leaning of the air-fuel ratio or misfire. Therefore, the combustibility of the air-fuel mixture is ensured in good condition.
Then, thereafter, while the stratified charge of the air-fuel mixture is favorably performed by the fuel for the stratified charge combustion, the air-fuel ratio of the air-fuel mixture is significantly increased by the full opening of the throttle valve 9, and the fuel efficiency is remarkably improved. Will be aimed at.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the overall structure of a stratified charge combustion control system for an engine according to the present invention, where 1 is an engine, 2 is a piston 3 which is slidably inserted in a cylinder 3 of the engine 1, and a recess 2a is formed on the top, Reference numeral 4 denotes a combustion chamber formed by the piston 2 so that the volume thereof is variable. One end of the combustion chamber 5 communicates with the atmosphere through an air cleaner 6, and the other end opens into the combustion chamber 4 to intake air from the engine 1
An intake passage 7 for supplying the exhaust gas to the combustion chamber 4, one end of which is open to the combustion chamber 4 and the other end of which is an exhaust passage for discharging exhaust gas to the atmosphere. Is provided with a throttle valve 9 for controlling the amount of intake air, and the throttle valve 9 and the downstream side of the surge tank 8 are for uniformly distributing and injecting fuel into the combustion chamber 4 for injection and supply. A fuel injection valve 10 for uniform combustion is provided. Further, at the top of the combustion chamber 4, the recess 2a of the piston 2 is provided.
A spark plug 11 that ignites the air-fuel mixture in the combustion chamber 4 facing the
Further, a fuel injection valve 12 for stratified combustion is arranged to inject and supply fuel unevenly only around the spark plug 11 in the combustion chamber 4. In the figure, reference numeral 15 is an intake valve provided at the opening of the intake passage 5 to the combustion chamber 4, 16 is an exhaust valve provided at the opening of the exhaust passage 7 to the combustion chamber 4, and 17 is an exhaust gas. It is a catalyst device for purifying exhaust gas, which is arranged in the middle of the passage 7.

Further, the throttle valve 9 is connected to a stepper motor 20 as an opening adjusting means for adjusting the opening of the throttle valve 9, and the fuel injection valve for uniform combustion is also connected.
A fuel pump 22 is connected to 10 through a regulator 21 that adjusts the fuel pressure to the fuel injection valve 10 for uniform combustion, while the fuel injection valve 12 for stratified combustion is connected to the fuel injection valve 12 for stratified combustion. An injection pump 23 that supplies fuel to the fuel injection valve 12 is connected. Further, the ignition plug 24 has an ignition coil 24
Are connected.

Further, 28 is a load sensor that detects the load state of the engine 1, 29 is a rotation speed sensor that detects the engine speed, and 30 is a predetermined angular position of the crankshaft of the engine 1 (for example, the piston top dead center position of a predetermined cylinder). TD that detects the reference position
C sensor, 31 is a water temperature sensor that detects the engine cooling water temperature, 32 is an intake air temperature sensor that detects the temperature of intake air, and 33 is an accelerator pedal opening that detects the accelerator opening (operation amount) of the accelerator pedal (accelerator operating member). The load sensor 28 and the rotation speed sensor 29 constitute a driving state detecting means 34 for detecting the driving state of the engine 1.

The detection signals of the above six sensors 28 to 33 are CP
It is input to the controller 35 that contains U, RAM, etc.
The controller 35 controls the stepper motor 20, the fuel injection valve 10 for uniform combustion, the injection pump 23, and the ignition coil 24, respectively, to control the throttle valve opening, the amount of fuel during uniform combustion, and the amount of fuel during stratified combustion. In addition, the ignition timing of the air-fuel mixture is adjusted.

Next, the operation of the controller 35 will be described based on the control flow of FIGS. First, starting from the control flow of FIG. 3, after initialization in step S ₁ , the above six sensors 28 to 33 (load, rotation speed, crank angle, cooling water temperature, intake air temperature and accelerator pedal opening are started in step S _2. Fill in the detection signal from degrees), it is determined whether or not the time of engine start by the state of the starter in the step S _3, if the YES at engine starting, the starting correction routine of Figure 7 at step S ₄ Then, the fuel supply to the engine 1 and the ignition timing are adjusted according to the engine start.

In the case of NO after engine start at the step S _3, in order to determine when steady state or accelerating, the change rate d .theta.a / dt of the degree of opening of the accelerator pedal in step S ₅ (not shown) The magnitude is compared with a predetermined value α ₁ corresponding to acceleration, and d θa / dt ≧ α ₁
Of the time of acceleration YES, the after traveling especially acceleration correction routine in step S ₆ (not shown), steps S ₇ and S S ₈
Based on the load signal and the engine speed signal, the first operating range (stratified combustion range) shown in FIG. 9 or the second operating range different from the first operating range (uniform combustion range (including start-up)) ) Or the third operating range (transitional range between stratified combustion and uniform combustion), and if it is the first operating range, the fourth operation is performed in step S ₉ .
The process proceeds to stratified combustion routine shown in FIG., In the second operating region proceeds to homogeneous combustion routine shown in FIG. 5 in step S _10, when the third operating region is reduced torque shock combustion switching For this purpose, the process proceeds to the transition region routine shown in FIG. 6 in step S ₁₁ .

Next, in order to explain the stratified charge combustion routine of FIG. 4, "1" is added to the counter n ₁ (initial value = 0) to measure the stratified charge combustion time in step S _S1 , and then the stratified charge combustion is performed in step S _S2. The fuel injection timing Inj.T (s) in the region is calculated to be in the latter half of the compression stroke based on the injection timing map for stratified charge combustion in Fig. 10 (a), and the fuel in the stratified charge region is calculated in step S _S3. The injection amount Qf (s) is calculated and set so as to increase in accordance with the increase in the accelerator pedal opening θa based on the injection amount map for stratified combustion in FIG. Further, in step S _S4 , the ignition timing Ig.T (s) in the stratified charge combustion region is set based on the ignition timing map for stratified charge combustion in FIG.
And the advance angle is adjusted according to the increase of the engine speed, and in step S _S5 , the ignition period Ig.Dr (s) in the stratified combustion region is set on the basis of the ignition period map for stratified combustion of FIG. It is calculated and set so as to become longer as the opening degree θa increases.

Then, in step S _S6 , the fuel injection timing from the fuel injection valve 12 for stratified charge combustion is set so as to match the injection timing Inj.T (s), and in step S _S7 , the fuel injection amount is set to the above fuel injection. The amount Qf (s) is set, and the stepper motor 20 is controlled so that the opening of the throttle valve 9 is fully opened to remarkably increase the air-fuel ratio of the air-fuel mixture and reduce the pumping loss of the engine 1. After that, the ignition timing Ig.T (s) set above in step S _S8
Wait until the ignition timing is reached, the ignition coil 24 is actuated and controlled in step S _S9 , and the ignition at the ignition plug 11 is made to this ignition timing Ig.T.
While continuing from (s) for the ignition period Ig. Dr (s), at step S _S10 , the fuel injection timing (Inj.T
Wait until it becomes (s), and in step S _S11 , the injection pump 23
The injection amount Qf from the fuel injection valve 12 for stratified charge combustion
The fuel (s) is injected and supplied around the spark plug 11 in the combustion chamber 4.

Then, thereafter, in order to cope with the generation of carbon due to the stratified combustion of the air-fuel mixture, the value of the counter n ₁ is determined in step S _S12 , and the value n ₁ is a predetermined time when the amount of carbon deposited on the spark plug 11 is large. If it is less than α ₂ , the carbon deposition amount is small, so the process returns immediately. On the other hand, if YES with a large carbon deposition amount, n ₁ ≧ α ₂ , this adhered carbon is burned uniformly in the air-fuel mixture. Step to burn off with
Counter n ₂ for measuring combustion switching time in S _S13 (initial value = 0)
After adding "1" to, the detection signals from the six sensors 28 to 33 are input in step S _S14 to detect the operating conditions of the engine 1, and in step S _S15 the uniform combustion routine of FIG. To start the uniform combustion of the air-fuel mixture, and then determine the value of the counter n _{2 in} step S _S16 in order to grasp this forced uniform combustion time, and this value n ₂ is sufficient to burn out the carbon. When the preset time is less than α ₃ (n ₂ <α ₃ ), the above uniform combustion is continued, and the return is performed only after the burning removal of the YES carbon of n ₂ ≧ α ₃ .

Next, to explain the uniform combustion routine of FIG. 5, the fuel injection timing Inj.T (h) in the uniform combustion region is determined based on the injection timing map for uniform combustion of FIG. 11 (a) in step S _H1 . am with calculated so that the intake stroke first half, the step S accelerator pedal opening based on the injection quantity map for homogeneous combustion in the drawing the fuel injection quantity Qf (h) in a homogeneous combustion zone in _H2 (b) theta
The calculation is set so that the amount is increased according to the increase of a. further,
In step S _H3 , the ignition timing Ig.T (h) in the uniform combustion region is determined according to the decrease in the accelerator pedal opening θa and the increase in the engine speed based on the ignition timing map for uniform combustion in FIG. The ignition timing Ig.Dr (h) in the uniform combustion region is adjusted in step S _H4 in accordance with the increase in the accelerator pedal opening θa based on the ignition period map for uniform combustion in FIG. Set the calculation so that it will increase.

After that, at step S _H5 , the opening θt of the throttle valve 9
Based on the throttle valve opening map of FIG. 10, (h) is calculated and set so as to increase with the increase of the accelerator pedal opening θa (constant opening at startup), and this throttle valve is set at step S _H6. Stepper motor 2 so that the opening becomes θt (h)
0 is controlled.

Then, in step S _H7 , the fuel injection timing In set above is set.
After waiting for j.T (h), in step S _H8 , the fuel injection valve 10 for uniform combustion injects fuel of the combustion injection amount Qf (h) into the combustion chamber 4 from the first half of the intake stroke, This fuel is evenly distributed and supplied into the combustion chamber 4, and step S
_H9 in waiting to become the air-fuel mixture ignition timing Ig.T (h), and controls the operation of the ignition coil 24 at step S _H10, the ignition timing of the ignition of the ignition plug 11 Ig.Dr (h) Continue for a while and return.

Next, to explain the transition region routine of FIG. 6, in step S _T1 , the fuel injection timing Inj.T (h) in the uniform combustion is set to the 11th time.
Based on the injection timing map for uniform combustion shown in FIG. 10 (a), the intake stroke is calculated in the first half, and the fuel injection timing Inj.T (s) for stratified charge combustion at step S _T2 is shown in FIG. 10 (a). It is calculated to be in the latter half of the compression stroke based on the injection timing map for stratified charge combustion. Further, in step S _T3 and step S _T4 , the fuel injection amount from each of the combustion injection valves 10 and 12 for uniform combustion and stratified charge combustion is within this transition region (third operating region) as shown in FIG. The fuel injection amount Qf (h) in the uniform combustion and the fuel injection amount Qf in the stratified charge combustion are gradually changed.
(S) and (s) are calculated based on the injection amount maps of FIG. 11 (b) and FIG. 10 (b), respectively, and then the fuel amount Qf (h) is reduced and the fuel amount Qf (s) is corrected. Correct the weight loss.
Furthermore, in order to make the ignition timing of the air-fuel mixture in this transition region the same as the ignition timing in the uniform combustion region, the ignition timing Ig.T (h) in uniform combustion is set in FIG. 11 (c) in step S _T5 . to calculate on the basis of the ignition timing map for the homogeneous combustion, calculated and set based on the ignition period in the homogeneous combustion in step S _T6 Ig.Dr a (h) in the ignition period map for homogeneous combustion in the diagram (d) Then, at step S _T7 , the opening θt of the throttle valve 9
The (h) is calculated set based on the throttle valve opening degree map in Figure 12, the throttle valve opening θt at step S _T8
The operation of the stepper motor 20 is controlled so as to become (h).

Thereafter, at step S _T9 , the fuel injection timing and the injection amount from the fuel injection valve 12 for the stratified combustion match the fuel injection timing Inj.T (s) and the fuel injection amount Qf (s) during the stratified combustion, respectively. After setting the fuel discharge timing and discharge amount from the injection pump 23, wait for the fuel injection timing Inj.T (h) in uniform combustion in step S _T10 , and then drive the fuel pump 22 in step S _T11. The fuel injection valve 10 for uniform combustion injects fuel of a fuel injection amount Qf (h) into the combustion chamber 4 from the first half of the intake stroke, and this fuel is evenly distributed and supplied throughout the combustion chamber 4. , Waiting for the ignition timing Ig.T (h) for uniform combustion in step S _T12 ,
_{At T13} , the operation of the ignition coil 24 is controlled to continue the ignition at the ignition plug 11 for the ignition period Ig. Dr (h).

Then, in step S _T14 , fuel injection timing In in stratified charge combustion
waiting to be j.T (s), step S _T15 fuel injection fuel for stratified combustion of the fuel injection amount Qf by driving the intake stroke late to the compression stroke immediately before injection pump 23 (s) valve 12
From this, the fuel is injected and supplied around the spark plug 11 in the combustion chamber 4, and the process returns.

Next, to explain the starting correction routine of FIG. 7, after inputting the engine speed N and the accelerator pedal opening θa during cranking in step S _C1 , uniform combustion of the air-fuel mixture is performed during this cranking. In order to improve the startability, the fuel injection timing Inj.T (h) is calculated in step S _C2 so as to be in the first half of the intake stroke based on the injection timing map for uniform combustion in FIG. 11 (a). In step S _C3 , the fuel injection amount Qf (h) is calculated and set so as to be larger than the injection amount after starting based on the injection amount map for uniform combustion in the same figure (b), and in step S _C4 the ignition timing Ig .T (h) is advanced based on the ignition timing map for uniform combustion shown in FIG. 11C according to the decrease in the accelerator pedal opening θa and the increase in engine speed, and the ignition period Ig is adjusted in step S _C5. .Dr (h) is the ignition period for uniform combustion shown in (d) of FIG. Based on the map, the ignition timing after starting is set to be shorter than the ignition timing, and then, in step S _C6 , the opening degree θt of the throttle valve 9 is set to a predetermined value of the minute opening degree based on the throttle valve opening map of FIG. The stepper motor 20 is actuated and controlled so that the throttle valve opening degree θt is reached by setting a constant value of α ₅ .

Then, after waiting for the fuel injection timing Inj.T (h) set above in step S _C7 , the fuel of the fuel injection amount Qf (h) is fed from the fuel injection valve 10 for uniform combustion in step S _C8. Is injected and supplied into the combustion chamber 4 from the first half of the intake stroke, and this fuel is uniformly distributed and supplied into the combustion chamber 4, and the ignition timing Ig.T (h) of the mixture is reached in step S _C9. After that, the operation of the ignition coil 24 is controlled in step S _C10 to ignite the spark plug 11 in the ignition period Ig. Dr.
Continue during (h), then determine the position of the starter in step S _C11 , and repeat the above operation when cranking YES at the ON position to wait for engine complete explosion,
After the complete explosion of the engine (in the case of NO), in order to continue the uniform combustion of the air-fuel mixture for a predetermined time thereafter, after inputting the engine speed N and the accelerator pedal opening θa again in step S _C12 , step S _C13 Then, "1" is added to the counter n ₃ for measuring the duration time of uniform combustion, and in step S _C14 , the above fifth
The routine proceeds to the uniform combustion routine shown in the figure to perform uniform combustion of the air-fuel mixture, and thereafter, in step S _C15 , the value of the counter n ₃ is compared with the set value α ₆ corresponding to the predetermined time T ₁ until the engine stabilizes, and n ₃ If <α _6, the above uniform combustion is continued to wait for the engine to stabilize, and after the predetermined time T ₁ of YES for n ₃ ≧ α ₆ , the homogeneous combustion of the air-fuel mixture is changed to the stratified combustion. Go to step S _{C16 and} subsequent steps.

Then, in step S _C16 , the engine speed N and the accelerator pedal opening θa are input again, and then in step S _C17 the first
It is determined whether or not it is in the operating range (stratified combustion range), and if NO is not in the first operating range, considering the case of starting immediately after complete explosion,
When it is in the second operation range (uniform combustion range) in step S _C18 , the process proceeds to the uniform combustion routine of FIG. 5 to perform uniform combustion in step S _C19 , while when it is in the third operation range (transition range), At S _C20 , the routine proceeds to the transition region routine of FIG. 6 to gradually switch the combustion state of the air-fuel mixture.

Then, when in the first operating region normally (stratified combustion range) at step S _C17, to switch gradually stratified combustion from homogeneous combustion, the routine proceeds to a sixth view of a transition region routine in step S _C21 uniform After gradually reducing the uniform fuel amount Qf (h) from the fuel injection valve 10 for combustion and gradually increasing the stratified fuel amount Qf (s) from the fuel injection valve 12 for stratified charge combustion, at step S _C22 it is made uniform. When the value of the fuel amount Qf (h) is determined, and Qf (h)> 0 is still injecting uniform fuel (NO
In the case of), the operation of reducing the uniform fuel amount Qf (h) and the increase of the stratified fuel amount Qf (s) are repeated, and Qf (h) = 0.
When the injection of uniform fuel is stopped in step _S23 , "1" is added to the counter n ₅ for measuring the safe time in step S _C23 , and then step
Comparing the magnitude with a predetermined value alpha ₈ corresponding to the value n ₅ the safety time T ₂ in S _C24, only if the YES safety time T ₂ has elapsed after the n ₅ ≧ α _8, the water temperature sensor 31 in step S _C25 based on the output from the grasp of the engine coolant temperature T _W, the cooling water temperature T _W compared predetermined temperature alpha ₉ and magnitude corresponding to the time of engine warmup, T _W
If YES when warming up the engine with ≧ α ₉ , step S
_{At C26} , the throttle valve 9 opening θ _T is quickly fully opened to return, and when the engine is cold when T _W ≧ α ₉ , the cold correction routine shown in FIG. 8 is executed at step S _{C27 to} prevent an engine stall. Go ahead and return.

That is, in the cold correction routine of FIG. 8, when the engine is cold, “1” is added to the counter n ₆ in step S _W1 , and then the throttle valve opening θ is set in step S _W2.
A minute value (α ₁₀ ×) corresponding to the counter value n ₆ from _T (h)
n ₆ ) (α ₁₀ ; coefficient) is subtracted, and the stepper motor 20 is driven so that the opening value θ _T (h) is _reached in step _{SW 3} , and the throttle valve opening θ _T (h) is gradually opened. Then, in step _SW4 , the above operation is repeated until the opening value θ _T (h) reaches a zero value, that is, until it is fully opened, and the process returns.

Therefore, the steps S _{7 to} S _{10 of} FIG. 3 and the steps S _{S1 to} S _S11 of the stratified charge combustion routine of FIG. 4 and the steps S _{H1 to} S _H4 , S _{H7 to} S _H10 of the uniform combustion routine of FIG. ,
When the engine operating condition is in the first operating region (stratified combustion region) in response to the output of the operating condition detecting means 34, fuel is injected from the fuel injection valve 12 for stratified combustion in the combustion chamber 4 in the latter half of the compression stroke. The fuel is supplied so as to be unevenly distributed only around the spark plug 11, and the air-fuel mixture containing the fuel is ignited at an ignition timing Ig.T (s) for stratified charge combustion to cause stratified charge combustion of the engine. The operating condition is the first operating range (stratified combustion range)
In the second operating region (uniform combustion region) different from that, fuel is injected from the fuel injection valve 10 for uniform combustion in the intake passage 5 from the first half of the intake stroke, and the fuel is evenly dispersed throughout the combustion chamber 4. The fuel supply means 42 is configured so that the air-fuel mixture containing the fuel is ignited at the ignition timing Ig.T (h) for uniform combustion to uniformly burn the air-fuel mixture.

Furthermore, by step S _S7 of the stratified charge combustion routine of FIG. 4 and steps S _H5 and S _H6 of the uniform combustion routine of FIG. 5,
When the engine operating condition is in the first operating region (stratified combustion region), the throttle valve opening θ _T is fully opened, while in the second operating region (uniform combustion region), the throttle valve opening θ _T is
An opening degree control means 44 for controlling the stepper motor 20 to configure _T to a required opening degree according to an increase or decrease in the accelerator pedal opening degree θa based on the throttle valve opening degree map of FIG.

In addition, in the start correction routine of FIG.
By S _C 15 to S _{C 17} , the transition of fuel injection supply from homogeneous combustion to stratified charge combustion transition at the time of transition from homogeneous combustion control of the mixed gas at engine start to stratified charge combustion control of the mixture at stable time thereafter. The fuel supply switching time detecting means 45 for detecting the time is configured, and the step
After the output of the fuel supply switching detection means 45 is received by S _{C21 to} S _C27 , the uniform fuel amount Qf (h) from the fuel injection valve 10 for uniform combustion becomes zero, that is, from the uniform fuel to the stratified fuel. The correction means 46 is configured to correct the control of the stepper motor 20 by the opening degree control means 44 so that the opening degree θ _T of the throttle valve 9 is fully opened after the supply switching to the throttle valve is completed.

Therefore, in the above embodiment, when the engine is started (second operation range), as shown in FIG. 14, the opening degree θ _T of the throttle valve 9 is very small at the same time as the cranking starts, as shown in FIG. together is adjusted to the opening degree alpha _5, injected into the combustion chamber 4 from the first half of the large amount of intake stroke fuel from the fuel injection valve 10 for the homogeneous combustion is corrected started as shown in FIG. (a) of the intake passage 5 As a result, the fuel-air mixture is uniformly burned in a state where the fuel is uniformly dispersed throughout the combustion chamber 4, so the engine speed shown in FIG. However, the engine can be started easily. At that time, the uniform fuel from the fuel injection valve 10 for uniform combustion is adjusted to the fuel amount Q ₁ necessary for the idle operation after the increase of the starting amount, and the stratified fuel amount from the fuel injection valve 12 for stratified combustion is shown in the same figure. It is zero as shown in (b).

When the engine reaches a stable state after a lapse of a predetermined time T ₁ , in the idle operation state, in order to switch from uniform combustion of the air-fuel mixture to stratified combustion, the uniform fuel amount of FIG. The ignition plug in the combustion chamber 4 based on the stratified fuel, that is, when the stratified fuel amount gradually increases and the uniform fuel amount becomes zero and the fuel supply switching is completed (point C in the diagram), that is, based on the stratified fuel. 11 If the combustible mixture unevenly distributed around 11 is completely switched to the stratified combustion, the opening degree θ _T of the throttle valve 9 is set to the stepper motor for the first time when the safety time T ₂ has elapsed from this point.
Since it is controlled to fully open at 20, the intake air amount increases during this stratified charge combustion, while maintaining good combustibility of the air-fuel mixture, the air-fuel ratio of the air-fuel mixture becomes significantly large, and fuel efficiency is improved. Is effectively achieved.

At that time, during the transitional transition from the homogeneous combustion of the air-fuel mixture to the stratified combustion, in a transitional state in which the uniform fuel injection continues, the opening degree θ _T of the throttle valve 9 is maintained at the minute opening degree α ₅ , Since the intake air amount does not suddenly increase with the full opening of the valve opening θ _T , the air-fuel ratio does not over lean or misfire during the transition of combustion switching, and good combustibility of the air-fuel mixture can be secured. it can.

Although the fuel injection valve 12 for stratified charge combustion is arranged in the combustion chamber 4 as desired in the above embodiment, the combustion injection valve 12 for stratified charge combustion is arranged immediately upstream of the intake valve 15 in the intake passage 5. Of course, the combustion injection valve 12 for stratified combustion or the fuel injection valve 10 for uniform combustion may be used as the other. In that case, the uniform combustion of the air-fuel mixture can be performed by advancing the fuel injection timing, and the stratified combustion of the air-fuel mixture can be performed by delaying the fuel injection timing.

Further, in the above embodiment, the case of combustion switching from uniform combustion at startup to stratified combustion has been described.
It can be applied in the same way even in the normal case of shifting from high rotation / high load to low rotation / low load, the point being the second operation range (uniform combustion range)
Can be applied when shifting from the first to the first operation range (stratified combustion range).

(Effect of the Invention) As described above, according to the present invention, when stratified combustion and uniform combustion of the air-fuel mixture are performed according to the engine operating state,
During the transition of fuel supply switching from homogeneous combustion to stratified charge combustion, the throttle valve opening is not fully opened until the fuel supply is completely switched, and the air-fuel mixture during stratified charge combustion is empty. Since the fuel ratio is remarkably increased, it is possible to prevent the air-fuel ratio from over leaning due to the abrupt increase of the intake air amount during the combustion switching transition and to ensure the combustibility of the air-fuel mixture.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 14 show an embodiment of the present invention, FIG. 2 is an overall configuration diagram, FIGS. 3 to 8 are flow charts showing the operation of a controller, respectively, and FIG. 9 is a first to a third diagram. Explanatory diagram showing the driving range, FIG. 10 (a) to (d) and FIG. 11 (a) to
(D) and FIG. 12 are diagrams showing various maps stored in the controller, FIG. 13 is a diagram showing injection amount characteristics of each fuel injection valve for stratified charge combustion and uniform combustion, and FIG. 14 is an operation explanation. It is a figure. 1 ... Engine, 9 ... Throttle valve, 10 ... Fuel injection valve for uniform combustion, 11 ... Spark plug, 12 ... Fuel injection valve for stratified combustion, 20 ... Stepper motor, 22 ... Fuel pump , 23 ... Injection pump, 28 ... Load sensor, 29 ... Rotation speed sensor, 33 ... Accelerator pedal opening sensor, 34 ... Operating state detection means, 35 ... Controller, 42 ... Fuel supply means, 44 ...... Opening control means, 45 ...... Fuel supply switching detection means, 46 ...... correction means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02D 41/04 310 BC

Claims (1)

[Claims] 1. An operating state detecting means for detecting an operating state of an engine, and a fuel supplied to the periphery of an ignition plug of a combustion chamber when the operating state of the engine is in a first operating range by receiving an output of the operating state detecting means. While making the air-fuel mixture stratified combustion,
A stratified combustion control system for an engine, comprising: a fuel supply means for supplying fuel to the entire combustion chamber to uniformly burn an air-fuel mixture when the engine operating state is in a second operating range different from the first operating range. The throttle valve opening is fully opened when the engine operating state is in the first operating range by receiving the outputs of the opening adjusting means for adjusting the opening of the throttle valve of the engine and the operating state detecting means. When in the second operating range, the opening control means for controlling the opening adjustment means so as to make the required opening according to the operation amount of the accelerator operation member, and the excessive switching of the fuel supply from the uniform combustion to the stratified combustion. For detecting the fuel supply switching time, and for receiving the output of the fuel supply switching time detecting means, the opening degree of the throttle valve is fully opened after switching the fuel supply from uniform combustion to stratified combustion. Stratified combustion control apparatus for an engine is characterized in that a correcting means for correcting the control of the opening degree adjuster according control means.